There are many situations in which it is both desirable and important to monitor the operability of machinery or other equipment components. Diagnostically assessing the operability of machinery can establish the running condition of the machinery in a fashion which is objective and scientific. For example, routine diagnostic procedures adopted by maintenance personal can help detect early signs of machinery malfunction or failure and, thus, lead to corrective and preventive measures to ensure machinery is functioning within desired operational parameters. Instances where such procedures can prove useful include the detection of early bearing failure, internal/external fluid leakage, cavitation in hydraulic systems, steam trap leakage, gear problems, bearing lubrication status, as well as a multitude of other machine diagnostic functions.
Predictive mechanical maintenance through vibration measurement of machinery illustrates one common approach to diagnosing and preventing machinery malfunctions, and it is known to employ different types of industrial vibration sensors, such as accelerometers, in conjunction with measuring instrumentation to help pinpoint and ultimately rectify mechanical deficiencies. A full range of accelerometers are available in the marketplace to meet unique applications. Accelerometers generally incorporate internal seismic masses which measure the acceleration of internal forces generated by internal moving parts, and they can be removably or permanently attached to surface mounting regions of machinery and coupled to measuring instrumentation, such as a vibration analyzer, to measure the motion of internal machine parts.
Another approach to diagnosing machinery and other types of mechanical systems is by using sensors which actually “listen” to structures and materials to detect acoustic emissions activity. Pressure vessels, storage tanks, heat exchangers, piping, reactors, aerial lift devices, nuclear power plants, and refrigeration systems illustrate some common examples in which acoustic emissions activity can be monitored. While acoustic emissions sensors, like accelerometers, are available in a wide variety of configurations and for a wide variety of particular applications, one particular application is the use of acoustic emission sensors in ultrasonic signal detectors to assess the existence of internal or external leaks associated with a system. Various types of ultrasonic leak detectors are disclosed in my following patents: U.S. Pat. No. 5,103,675 issued Apr. 14, 1992, U.S. Pat. No. 5,432,755 issued Jul. 11, 1995, U.S. Pat. No. 5,436,556 issued Jul. 25, 1995, U.S. Pat. No. 6,058,076 issued May 2, 2000, U.S. Pat. No. 6,079,275 issued Jun. 27, 2000, U.S. Pat. No. 6,128,959 issued Oct. 10, 2000, and U.S. Pat. No. 6,163,504 issued Dec. 19, 2000.
It has heretofore, however, been unknown to utilize an acoustic emission sensor in conjunction with measuring instrumentation, similar to the manner in which accelerometers have been employed, for the purpose of measuring sound internal to machinery or systems. By employing acoustic emission sensors which can be either permanently or removably mounted to appropriate surface regions of machinery, one can obtain useful information about the sound characteristics of the machinery which can facilitate calibration, maintenance and diagnostics. If desired, this approach can be used in conjunction with other known diagnostic and monitoring techniques as part of a routine maintenance schedule. The present invention is directed to meeting these needs, among others.